leiningen plugin doesn't list subcommands via `help`

[glenjamin]

The following is an except of my recent terminal session, before giving up and googling.

> lein cljfmt
Wrong number of arguments to cljfmt task.
Expected [command & paths]

> lein cljfmt help
Unknown cljfmt command: help

> lein cljfmt --help
Format Clojure source files

Arguments: ([command & paths])

> lein cljfmt
Wrong number of arguments to cljfmt task.
Expected [command & paths]

> lein help cljfmt
Format Clojure source files

Arguments: ([command & paths])

> lein cljfmt format
Unknown cljfmt command: format

I'll come back and look at adding a PR at some point - I'm having a yak shaving kind of day.